Orthogonal Frequency Division Multiplexing (OFDM) based networks are examples for such cellular radio communication networks with a frame structure showing a time and frequency extension. These networks use a multi-carrier transmission technique and are foreseen to be used as access technology in the fourth generation of wireless/mobile communication networks thanks to their ability especially in combination with MIMO/beamforming antenna technology to reach very high bit rates. OFDM offers a sensible alternative for high-speed mobile applications, and thus represents an important step for next generation mobile radio systems or for a 4th generation air interface to be defined in 3G LTE, 802.16e and 802.16m.
In multi-carrier systems as OFDM transmission systems, the transmitted data is split into a number of parallel data streams, each one used to modulate a separate sub-carrier. In other words, the broadband radio channel is subdivided into a plurality of narrow-band sub-carriers or subchannels, which are groups of sub-carriers, being independently modulated with e.g. QPSK, 16 QAM, 64 QAM or higher modulation order allowing higher data rate per sub-carrier. The sub-carriers allocation to a user consists either in consecutive (physically adjacent) sub-carriers allocation in a part of the frequency domain of the system also called frequency selective allocation or in allocation of sub-carriers spread over the entire frequency band of the system called frequency diverse allocation or PUSC in the context of WIMAX.
In such multicarrier systems, the sub-carrier frequencies can be allocated to a user channel on a short term basis (e.g. all 2 ms) as well as the modulation order per sub-carrier defining a transmission channel for each user should be updated on the same short term basis.
In order to exploit the best capacity of multicarrier systems, they are used with resource allocations following a frequency reuse 1 scheme. This means that the whole range of frequency sub-carriers are used in all cells and even in all sectors of one cell. Other frequency reuse schemes on the contrary foresee that the available frequency sub-carriers are not simultaneously used in the different sectors of one cell or in adjacent sectors of adjacent cells. Frequency reuse 3 scheme foresees for example that in a cell comprising 3 sub-sectors only one third of the available frequencies can be used in the first sector, another third in a second sector and the last third in the last sector.
The advantage of frequency reuse 1 schemes is the higher spectral efficiency which can be reached compared to frequency reuse 3, its disadvantage is a high and complex interference generated by users or base stations using the same resource at the same time.
It is a particular object of the present invention to provide a method for coping with the problem of interference in such a multicarrier system ensuring high data rates for the end-users.
Another object of the invention is to provide a corresponding base station adapted to implement the method.